The objectives of this proposal are to: 1) purify and structurally characterize the neutral glycosphingolipids and gangliosides of human leukemia cells; 2) develop high performance liquid chromatographic methods for the structural and quantitative analysis of these molecules; 3) find leukemia cell lines which will allow us to prove the possible biochemical mechanism(s) which regulate the expression of neutral glycosphingolipids in human leukocytes; 4) determine the structure of human leukocyte glycosphingolipids which are I, i blood group antigens and how the levels of the compounds vary with leukemogenesis; and 5) purify the structurally characterize the carbohydrate moiety of the glycoprotein which is expressed on chronic lymphocytic leukemia cells and recognized by the monoclonal antibody PI 153/3. To achieve these goals we will use the following methods: gas-liquid chromatography (GC); direct probe and combined GC-mass spectrometry; and a technique which combines the sensitivity of high performance liquid chromatography with the specificity of both endo- and exoglycosidases. The results of these analyses will enable us to determine the variations inglycosphingolipids among the different classes of human leukemia cells (lymphoid and nonlymphoid; T, B and null cells), and to make comparisons with those of normal leukocytes. It willalso be possible to determine if the gangliosides, which have previously been found only in normal human leukocytes, are present in leukemia cells, and whether other unique compounds exist in leukemic cells. The evaluation of I,i glycosphingolipids in human leukocytes will allow us to compare the structure of these antigens to those found in other tissues, and to determine how the structure and quantities of these compounds vary among normal and leukemic leukocytes. The structural characterization of the antigen recognized by the monoclonal antibody PI 1543/3, which recognizes only certain types of leukemia cells and does not bind to normal leukocytes, will provide valuable information on the specificty of this immunoglobulin.